A magnetic random access memory (MRAM) is a non-volatile memory which basically includes a magnetoresistive (MR) material, a sense line, and a word line. The MRAM employs the MR effect to store memory states. Magnetic vectors in one or all of the layers of MR material are switched very quickly from one direction to an opposite direction when a magnetic field is applied to the MR material over a certain threshold. According to the direction of the magnetic vectors in the MR material, states are stored, for example, one direction can be defined as a logic "0", and another direction can be defined as a logic "1". The MR material maintains these states even without a magnetic field being applied. The states stored in the MR material can be read by passing a sense current through the cell in a sence line because of the difference between the magnetic resistances of the two states.
To be useful in present day electronic devices, very high density arrays of magnetic memory cells are utilized in magnetic random access memories. In these high density arrays the cells are generally arranged in rows and columns, with individual cells being addressable for reading and writing operations by the selection of an appropriate row and column containing the desired cell. Also, orthogonal current lines are provided, one for each row and one for each column so that a selected cell is written by applying current to the appropriate row current line and the appropriate column current line. The problem that arises is that current applied to the row and column current lines for writing and/or reading a selected cell can effect the data stored in other cells which are not at the cross-over point.
Accordingly, it is highly desirable to provide methods of writing/reading magnetic random access memories which do not effect other cells in the memories.
It is a purpose of the present invention to provide a new and improved method of writing/reading magnetic random access memories, or arrays of magnetic memories, which does not adversely effect other cells in the memory or array.
It is another purpose of the present invention to provide a new and improved method of writing/reading magnetic random access memories, or arrays of magnetic memories, which has better selectivity and reproducibility.
It is a further purpose of the present invention to provide a new and improved method of writing/reading magnetic random access memories, or arrays of magnetic memories, which has more stable switching.